Kinetic Mechanisms of DNA Mismatch Repair Proteins

Wesleyan University, Middletown CT

Investigators

Abstract

The DNA mismatch repair system (MMR) maintains the integrity of the genome by locating and correcting errors in the double helix. Defects in MMR lead to high levels of mutagenesis; thus there is considerable significance in understanding the mechanism of this critical DNA repair process. The proteins responsible for MMR identify errors such as mismatched base pairs or base insertions/deletions made during DNA replication, and signal excision of the error-containing strand followed by DNA resynthesis. The project studies two essential MMR proteins, MutS, which recognizes the errors in DNA, and MutL, which signals initiation of strand excision. These proteins are highly conserved through evolution, and our research on both prokaryotic (Thermus aquaticus) and eukaryotic (Saccharomyces cerevisiae) MMR proteins will answer fundamental questions about their functions in diverse organisms. Specifically, fluorescence-based transient kinetics methods are being used to (a) measure the conformational dynamics of MutS and DNA during mismatch recognition, (b) examine the actions of MutL during initiation of strand excision, and (c) explore the connections between DNA replication and repair. Findings from this study will provide high-resolution mechanistic data that will complement high-resolution structural data on these proteins and thus increase our understanding of how they work to protect DNA. Broader Impacts: The broader impact of the project includes teaching and training of students in quantitative biological research and development of professional careers in the life sciences. In addition to graduate students, the PI's group generally has several undergraduates, including under-represented minority students, who are involved in all aspects of the project and often publish their findings in peer-reviewed journal articles. Furthermore, the PI is deeply involved in developing new approaches to incorporate science into the arts, humanities and social sciences curricula at her university. She co-teaches courses with Film Studies faculty (Making the Science Documentary) and Dance faculty (Body Languages-Choreographing Biology), and is currently leading a university-funded "Sciences Across the Curriculum" initiative to support creation of new team-taught courses that present substantive science content and scientific thinking in the context of other disciplines, thereby engaging non-science majors with science in more personally relevant ways.